The present invention relates generally to hot-gas cleanup systems and more particularly to filter holder and gasket assemblies that provide particulate barrier seals between the body of a candle filter element and the filter holder when coupled to a hot gas cleanup system support plate.
Modern industrial methods have resulted in a need for devices and systems that are capable of efficiently filtering high temperature combustion gases containing particulate material. In combustion turbine applications, for example, a combustion turbine uses energy generated from hot pressurized combustion gases produced by burning natural or propane gas, petroleum distillates or low ash fuel oil. When coal and other solid fuels are burned, particulates carried over from the combustion of such solid fuels can cause turbine blade erosion and fouling. An efficient system for filtering of such hot combustion gases would permit the use of such solid fuels. Examples of such filtering apparatus and systems can be found in U.S. Pat. Nos. 5,433,771 and 5,876,471.
Currently, various assemblies of commercially available candle filters are employed for application within hot gas filtration systems. For example, in co-pending application Ser. No. 09/393,561, filed Sep. 10, 1999 (Docket No. 99E7659), entitled xe2x80x9cFILTER ASSEMBLY FOR METALLIC AND INTERMETALLIC TUBE FILTERSxe2x80x9d, to Alvin, et al., there is taught the use of an integral metal filter failsafe-regenerator assembly; and in co-pending application Ser. No. 09/602,214, filed Jun. 23, 2000 (Docket No. 99E9210), entitled xe2x80x9cMULTIPURPOSE SINGLE EXTERNAL SEAL FILTER ASSEMBLY FOR METALLIC AND CERAMIC TUBE FILTERS WITH INTEGRAL LOCKING MEANSxe2x80x9d, to Alvin et al, there is taught the use of a single compression fit gasket for integral metal filter faisafe-regenerator assemblies.
With the development of advanced materials, the geometry of the candles has varied, particularly in the flange region, requiring modification to the fixturing and sealing arrangements for the individual elements within the filter housing, in order to provide an effective particulate barrier seal during use in high temperature applications for each candle configuration. Employing separate filter holder designs for each candle filter configuration adds considerable expense to such systems and is inefficient.
Accordingly, a new filter holder assembly design is desired that will securely mount candle filter elements with a wide variety of variably sized flange geometries, within existing hot gas filtration systems. Furthermore, such an improved filter holder is desired that can be effectively employed in high temperature, high pressure, oxidizing, as well as reducing gas process environments.
The present invention discloses a filter holder assembly for holding a candle filter element within a hot gas cleanup system pressure vessel. The filter holder assembly includes a filter housing with a peripheral sidewall defining an interior chamber therein. A generally annular spacer ring is provided in the assembly and is positioned within the interior chamber. The assembly of the present invention further includes at least one top compliant gasket separate and apart from the filter housing. This top compliant gasket is preferably positioned on a candle filter flange end top surface for providing a seal between the spacer ring and the filter flange top surface. In addition, the top gasket is positioned generally adjacent to the collar of the spacer ring.
The assembly of the present invention further includes a collar that extends axially from the spacer ring and forms a stepped portion between the collar and the outside diameter of the spacer ring. In the present invention, this stepped portion permits the top gasket to seat against the spacer ring during filtering or back-pulsing, thereby resisting disruption of gasketing that can compromise the filtering effectiveness of the filter holder assembly.